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<!DOCTYPE html>
<html>
<head>
<title>
oscillator-late-start.html
</title>
<script src="../../imported/w3c/web-platform-tests/resources/testharness.js"></script>
<script src="../../resources/testharnessreport.js"></script>
<script src="../resources/audit-util.js"></script>
<script src="../resources/audit.js"></script>
</head>
<body>
<script id="layout-test-code">
let audit = Audit.createTaskRunner();
let sampleRate = 44100;
let renderLength = 1;
let context;
let node;
// Test the oscillator node is rendered correctly when the start time of
// start() call is in the past in terms of the context time.
audit.define('initialize', (task, should) => {
should(
() => context = new OfflineAudioContext(
1, sampleRate * renderLength, sampleRate),
'Creating offline context for testing')
.notThrow();
should(() => {
// Set up a dummy signal path to keep the audio context running and
// spend processing time before calling start(0).
let osc = context.createOscillator();
let silent = context.createGain();
osc.connect(silent);
silent.connect(context.destination);
silent.gain.setValueAtTime(0.0, 0);
osc.start();
node = context.createOscillator();
node.connect(context.destination);
}, 'Creating graph for testing').notThrow();
task.done();
});
audit.define('test-late-start', (task, should) => {
// The node's start time will be clamped to the render quantum boundary
// >0.1 sec. Thus the rendered buffer will have non-zero frames.
// See issue: crbug.com/462167
let suspendTime = 0.1;
let suspendFrame = 128 * Math.floor(0.1 * context.sampleRate / 128);
context.suspend(suspendTime).then(() => {
node.start(0);
context.resume();
});
// Start rendering and verify result: this verifies if 1) the rendered
// buffer contains at least one non-zero value and 2) the non-zero value
// is found later than the first output sample.
context.startRendering()
.then(buffer => {
let channelData = buffer.getChannelData(0);
let nonZeroValueIndex = channelData.findIndex(x => x != 0);
should(
nonZeroValueIndex,
'The index (' + nonZeroValueIndex +
') of first non-zero output value')
.beGreaterThanOrEqualTo(suspendFrame);
should(
channelData.slice(0, suspendFrame),
'Output[0:' + (suspendFrame - 1) + ']')
.beConstantValueOf(0);
})
.then(() => task.done());
;
});
audit.run();
</script>
</body>
</html>